Absolute structure determination

This page concentrates on the discussion about a method described by Rob Hooft, Leo Straver and Anthony Spek that has been published in the Journal of Applied Crystallography in February 2008: J. Appl. Cryst. (2008). 41, 96-103. This method uses a combination of maximum likelihood estimation and Bayesian statistics to calculate:

• A value y, comparable to the value of the Flack x parameter, with its standard deviation. This does not assume any prior knowledge about the compound.
• A pair of values P2(right) and P2(wrong) expressing the likelihood that the given absolute structure is right or wrong, assuming the prior knowledge that the compound is enantiopure.
• A triplet of values P3(right), P3(twin) and P3(wrong) expressing the likelihood that the given absolute structure is right, that the crystal is a 50%/50% inversion twin, or that the absolute structure should be inverted. This assumes the prior knowledge that the crystal can not be an inversion twin with another ratio.

Further reading

• Bibliography of literature regarding absolute configuration determinations
• Frequently asked questions on the Bayesian statistics/Maximum likelihood method of determining absolute structure
• Presentations by the authors and by users of this method

Questions or suggestions